Hydrostatic coupling



Jan- 26, 1954 A. H. HAILER ET Al. 2,667,184

HYDROSTATIC COUPLING Filed Oct. 28, 1952 Patented` Jan. 26, 1954 HY DROSTATIO COUPLING Albert Henry Hailer, Isleworth, and Frank Stanley Saunders, London, England; said Hailer as.- signor to Alltools Limited, Brentford, England Application October 28, 1952, Serial N o. 317,188

Claims. priority, application Great Britain February 5, 1952 i claims, (C1. 137-791)l It is customary in instruments,` for example pressure gauges and thermometers, which depend on the transmission of hydrostatic pressure from a pressure source to a gauge or the like, to use apipe for transmitting the pressure and to couple the pipe to the pressure source and to the gauge by couplings of the screwed union and nipple type. Uncoupling for the purpose of replacing a gauge or pipe then entails some loss of' liquid and there are circumstances, in which such loss of liquid cannot be tolerated.,

The object of this invention is to provideV a coupling between two members in a line for transmitting hydrostatic pressure, which, when uncoupled, will permit no leakage. of iluid andV which, when coupleckwill afford little, if any,.impediment to movement of liquid in either member in response to changes in. pressure or temperature.

The invention accordingly provides a coupling between two members in a conduit, for transmitting hydrostatic pressure comprising, in. combination with a spigot end o n eachmember, a flexible diaphragm covering each spigot endand forming aliquid tight joint therewith at its. periphery and a detachable coupling member for securing the tWo spigot ends together with` the, diaphragms in close abutment. When the members are uncoupled, the diaphragms will prevent leakage of liquid from them. When they are coupled, together, the diaphragmswill.abutclosely and serve toI transmit pressure fromtheliquid contained in one member to that contained in theA other member. There should be no pressurein the system when coupling or uncoup1ing,.s0 that the diaphragms will thenbe iiaty and will abut closely over their whole arealwhen the coupling is made. Space is provided in each spigot end to permit of the necessary small movement of the diaphragms when the systemY is subjected to pressure.r If desired, provision may bemade for escape of air from between the diaphragms.

Thel invention is of particular utility for establishing, ina hydrostatic weghingfmachine of the kind described in U. S. Patenty No. 2,392,702, couplings between the pressure generating unit, to Whichthe. object, to be weighed is. applied, and the gauge and a length. of` pipe line. connecting the pressure generating unit and the gauge. One such application of. the invention will now be described inv detail, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 isa side view, of the. weighingmachine,

Fig. 2 is asection cnay larger scale, on the line II-IIinFig.. l,

'lli

Fig. V3 is a section on the lineIII-III` in Fig.. 2, and

Fig. 4 is a view, similar to.v Fig. 2,. but showing the two conduit members uncoupled.

The weighing machine comprises a pressure generating unit It having a platformA IlV to. support the object to be weighed, a gauge i2 having a pointer I3y for indicating. the weight of the object, and a capillary tube` t4 for transmitting hydrostatic pressure fromr the. generating unit H3 to the gauge l2.

Detachable couplings l=5vconnect spigot ends l 'i onr each end of the capillary tube i4A to spigot ends i6 projecting respectively from theA unit lil and the gauge l2. These couplings are. precisely similar, and accordingly only the coupling it. connecting the tube i4 and the-gauge t2 is illustrated in detail in the drawings;

The spigot end I6 has a narrowcentral bore IB for the passage of the pressure transmitting liquid, which opens intoa conical cavity 2U. The spigot end has a screwedshank: 2|- Which screws into the gauge I2, a packing washer 22 being inserted between the two parts. Theopenmouth of the cavity 2t is sealed by a rubber diaphragm joint with thespigot endi Iii.y Tothis end,4 the edge portion of the diaphragm` is; turned over to lie parallel with theaxis of. the spigot endi 6 and formed with a peripheral bead. 23 which is retainelt` in a circumferentialgrooveinthe. spigot end The spigotend Il hasanarrow centralborefZ'll, intol which is press iitted thel end. of the; capillary tube I. The bore'zl communicateswithza conical cavity t5, similar to thefcavity'ii;V The` end of the spigot end Il' isr sealed byv a rubber diaphragm 25, precisely similar tothe diaphragm 59 and secured to the spigot end l'lfr by a beaded rim 2l? on the diaphragmr which engages a circumferential retaining groove in they spigot end. Screwed to each of the spigot ends l1 is a length of tubing 2S for protecting the adjoiningv end of the. capillary tube lll.,

The spigot end i6y is externally threaded and, toy secure. the spigot ends: together a. union nut 29 havingn a flange. 35i, isy tted over theY spigot end l1 and screwed to thespigotfend I6. as shown in Fig. 2. Tubular metal. distance pieces 3i., 32 are iitted to the spigot ends each ofu theseV surrounding. the parts of the. associated diaphragm which extendbetweenthe beaded edgefof the. diaphragm and the at portion thereof which closes the spigot end.4 These' distance, pieces. 3i, 32 serve to.v limit.y the;` clampingl pressure' whiclr` can be applied to the diaphragms. This is of importance since if an excessive clamping pressure were applied by the spigot ends I6, I1 to the peripheral portions of the ilat surfaces of the rubber diaphragms, I9, 26 the rubber would flow inwardly and the diaphragms would become slack and incapable of transmitting changes in hydrostatic pressure from one spigot end to the other. An air escape hole 33 is provided in the union nut 29, opposite the abutting ends of the distance pieces 3 I, 32, to permit of escape of air which may be trapped between the diaphragms I9, 26. Each spigot end has an air bleeding vent 34 which leads from the conical cavity therein, at a point near the periphery of the diaphragm, to an outlet 35 containing a ball valve 36 and a bleed screw 31 (see especially Fig. 3) which can be screwed in to hold the ball valve 36 against a seating 38.

By means of the couplings I5 a long pressure transmitting capillary tube I4 may be coupled between the pressure generating unit I0 and the gauge I2. This narrow tube I4 may easily be inserted through small openings to connect the pressure generating unit to a remote gauge. If the capillary tube I4 should fracture, there will be no leakage of liquid from the pressure generating unit I0, despite the presence of pressure therein, since the diaphragms will be moved out-- wardly into the conical cavity in the spigot end I1 attached to the capillary tube and supported thereby against the pressure.

In addition to permitting of uncoupling of the gauge or pipe line without loss of liquid, and of safeguarding against loss of liquid from the pressure generating unit and gauge in the event of fracture of the pipe, the invention has the advantage that, since three separately sealed liquidcontaining sections are involved, these may contain different liquids. Thus, in the case of a remote reading thermometer, it may be desired to use mercury in the pressure generating unit and also in the capillary tube but to use oil in the gauge. Furthermore, since the diaphragrns can flex to some extent,the effects of thermal expansion or contraction of the liquid in the capillary tube are reduced to a minimum.

The three sections of the system are filled with liquid independently, air being bled out through the air bleeding vents during lling. The diaphragms are flat when there is no pressure but will deflect as pressure causes movement of the liquid. This movement for the purposes mentioned is small, the conical cavities provided in the spigot ends being suicient in volume to cater for the necessary displacement of liquid,

What we claim as our invention and desire to secure by Letters Patent is:

l. In a conduit for transmitting hydrostatic pressure, the combination of two separable conduit members each having a spigot end, the spigot end of each conduit member having a narrow bore and a wider recess communicating with said bore, a pair of flexible diaphragms, each diaphragm covering one of said spigot ends and having a body portion covering and sealing the recess in said spigot end and having a cylindrical peripheral` portion extending axially of said spigot end in contact with the outer Wall of said spigot end and terminating in an enlarged bead accommodated in the circumferential retaining groove in said outer wall, said bead constituting the sole means for securing said diaphragm to said spigot end when said conduit members are separated, a detachable coupling member fitted over the ends of said conduit members to couple them together end to end with the body portions of said diaphragms in close abutment, and spacing means between said coupling member and the cylindrical portions of said diaphragms for relieving `the diaphragms of clamping pressure, said spacing means and coupling member permitting of escape of air from between said diaphragms during coupling of said conduit members.

2. In a conduit for transmitting hydrostatic pressure, the combination of two separable conduit members each having a spigot end, the spigot end of each conduit member having a narrow bore and a wider recess communicating with said bore, a pair of flexible diaphragms, each diaphragm covering one of said spigot ends and having a body portion covering and sealing the recess in said spigot end and having a cylindrical peripheral portion extending axially of said spigot end in contact withthe outer wall of said spigot end and` terminating in an enlarged bead accommodated in a circumferential retaining groove in said outer` wall, said bead constituting the sole means for securing said diaphragm to said spigot end when said conduit members are separated, a union nut for engaging said spigot ends and securing them detachably together with the body portions of said daphragms in closev abutment, and a pair of, tubular distance pieces, one adapted to iit Within each spigot end around the cylindrical portion of the diaphragm on said spigot end, said distance pieces cooperating to limit the clamping pressure applied by the union nut to the diaphragms, and the union nut having an air escape hole which, in the operative position of said nut, is opposite the abutting ends of said distance pieces. l

3. In a conduit for transmitting hydrostatic pressure, the combination of two separable conduit members each having a spigot end, a pair of Yilexible diaphragms, each diaphragm having a body portion coveringand sealing one of said spigot ends and having a cylindrical peripheral portion extending axially of said spigot end in contact with the outer wall of said spigot end and terminating in an enlarged bead accommodated in a circumferential retaining groove in said outer wall, said bead constituting the sole means for securing said diaphragm to said spigot end when said conduit members are separated, each of said spigot ends having an air bleeding vent leading from a point therein near the margin of the body portion of the diaphragm for allowing air to escape during lling of the associated conduit member with liquid, a union nut for engaging said spigot ends and holding them detachablyV together with the body portions of said diaphragme in close abutment, and spacing means adapted to nt between said spigot ends and within said union nut to relieve the diaphragms of clamping pressure when coupled together', said spacing means and union nut permitting of escape of air from between said diaphragms during coupling of said conduit members.

4. In a conduit for transmitting hydrostatic pressure, the combination of two separable conduit members each having a spigot end, the spigot end of each conduit member having a narrow bore and a wider recess communicating with said bore, a pair of flexible diaphragms, each diaphragm closing one of said spigot ends and having a body portionv closing and sealing the recess in said spigot end and having a cylindrical peripheral portion extending axially of said spigot end in contact with a Wall of said spigot end and terminating in an enlarged bead engaging a circumferential groove in said Wall, said bead serving to secure said diaphragm to said spigot end when said conduit members are separated, and a detachable coupling member` fitted over the ends of said conduit members to couple them together end to end with the body portions of said diaphragms in close abutment and without the application to said diaphragms of the full clamping pressure of said coupling member, said coupling member permitting of escape of air from between said diaphragms during coupling of said conduit members.

ALBERT HENRY HAILER.

FRANK STANLEY SAUNDERS.

References Cited in the le of this patent UNITED STATES PAIENTS Number Name Date 5 2,091,207 Kingsbury Aug. 24, 1937 2,219,566 Sauzedde Oct. 29, 1940 2,392,702 Saunders Jan. 8, 1946 FOREIGN PATENTS 10 Number Country Date 761,812 France v Dec. 14, 1932 577,283 Great Britain May 13, 1946 

